Forget the bats, spiders, and black cats. If you want to learn about some truly spooky creatures this Halloween, keep reading!
Many people are familiar with insect predators, like lady beetles/ladybugs, that eat other insects. But not many know about another type of good bug or “natural enemy”—parasitoids. These creepy insects can help reduce pest populations by parasitizing them.
What is a parasitoid?
Parasites such as fleas and ticks live and feed on their host without killing it. Parasitoids are like parasites but DO eventually kill their host. Parasitoids live and feed in or on a host and can develop either inside or outside of the host's body. Most parasitoid insects are small flies and wasps. But don't worry—they won't harm you!
Some common insect parasitoids
Aphidiidae wasps attack aphids. Females lay 1 egg in about 100 aphids. About a week later, the egg hatches and the larva begins feeding on the inside of the aphid. This kills the aphid and causes its skin to become crusty, bronze-colored, and puffy (mummified). After pupating inside the aphid, the wasp chews a rounded hole and emerges from the aphid mummy.
Tachinidae flies feed on beetles, caterpillars, grasshoppers, true bugs, and others. Some females insert an egg into the host or glue eggs on the host's body. Others lay eggs on plants or in the soil where plant-feeding or soil-dwelling insects will consume them. Their larvae are maggots that feed inside the host.
Goniozus legneri feeds on caterpillars, such as the navel orangeworm. Females lay 1 to 20 eggs into the host. Upon laying the eggs, females will consume the exuding body contents. Developing larvae will also consume the host's insides.
Curious about other spooky creatures? Check out the recording of the UC IPM webinar Spooky Insects: A Halloween Special to learn about more insect predators and parasitoids, blood sucking creatures, and entomopathogenic fungi!
For more information on natural enemies, visit the resources below:
- Parasitoids section in Natural Enemies Gallery
- Parasites of Insect Pests
- Natural Enemies and Beneficial Insects: What Are They? (webinar)
- Pest Notes: Biological Control and Natural Enemies of Invertebrates (fact sheet)